Laminated indicator plaques

ABSTRACT

A LAMINATED INDICATOR PLAQUE HAS V-SHAPED INDICIA CUT THROUGH AN OPAQUE LAYER AND INTO A TRANSLUCENT LAYER SO THAT LIGHT FROM A SOURCE BEHIND THE TRANSLUCENT LAYER IS REFLECTED FROM THE WALLS OF THE INDICIA IN THE OPAQUE LAYER.   D R A W I N G

May 11, 1971 w, p oss ETAL 3,578,538

\ LAMINATED INDICATOR PLAQUES Filed June 12, 1968 Ill/I/l/ United States Patent 3,578,538 LAMINATED INDICATOR PLAQUES Kenneth Wheatley Prosser and John Vipond Wallace, Luton, England, assignors to The English Electric Company Limited, London, England Filed June 12, 1968, Ser. No. 736,380 Claims priority, application Great Britain, June 15, 1967, 27,650/ 67 Int. Cl. B32b 3/10; G09f 13/06, 13/08 US. Cl. 161-6 Claims ABSTRACT OF THE DISCLOSURE A laminated indicator plaque has V-shaped indicia cut through an opaque layer and into a translucent layer so that light from a source behind the translucent layer is reflected from the walls of the indicia in the opaque layer.

This invention relates to indicators, for example for instrument panels and the like, including a laminated indicator plaque arranged to transmit light from a source behind the plaque through indicia formed at the front of the plaque; to the plaques themselves; and to methods of making them.

More particularly, the invention is concerned with laminated indicator plaques, indicators including such plaques, and methods of making them, in which the plaque is of the kind including a translucent layer behind a first opaque layer, indicia being formed through the layer or layers in front of the translucent layer and penetrating part-way into the translucent layer.

The word translucent as used herein includes transparent, and opaque means incapable of transmitting any light or more than a negligible amount of light.

According to the invention in one aspect, a laminated indicator plaque includes a translucent layer behind a first opaque layer having a substantially higher reflectivity to visible light than the translucent layer, wherein indicia, formed through the layer or layers in front of the translucent layer and penetrating part-way into the translucent layer, have a cross'section substantially in the form of a V, the apex angle of which is such that light transmitted through the translucent layer from behind is reflected from those portions of the walls of the indicia formed on said first opaque layer.

This arrangement provides indicia which are viewed principally by means of the light reflected from the walls of the indicia, the only transmitted light reaching the eye appearing in the form of a very thin bright line in the middle of the indicia, i.e. along the apex of the V shaped groove or grooves which constitute the indicia.

The said first opaque layer is of a light colour, preferably white.

The plaque preferably includes a further opaque layer of substantially non-reflecting material, in front of said first opaque layer.

The said further opaque layer may comprise a layer of paint or ink, or it may be a sheet. In particular, the further opaque layer may be of polyvinyl chloride (PVC') paint or ink (which may be matt) or of PVC sheet. Sheet may be used where its use is desirable in preference to paint or ink, for example for reasons of mechanical strength.

The translucent layer, or the first opaque layer (but preferably both) comprise unplasticized PVC.

A protective layer of translucent material, substantially harder than the layer next behind it, is preferably arranged as the outside layer on the front of the plaque.

The plaque may be flat or curved.

According to the invention in another aspect, an indicator consists of an electroluminescent panel having a laminated indicator plaque according to the invention on the front thereof.

According to the invention in a further aspect, a method of making a laminated indicator plaque including a translucent layer behind a first opaque layer having a substantially higher reflectivity to visible light than the translucent layer, includes the step of engraving indicia so as to give the indicia a cross-section substantially in the form of a V, so that the indicia extend through the layer or layers in front of the translucent layer and penetrate part way into the translucent layer, and so that the apex angle of the V is such that light transmitted through the translucent layer from behind can be reflected from those portions of the walls of the indicia formed on the said first opaque layer.

The method preferably also includes the step of applying to the front of said first opaque layer a further layer, of substantially non-reflecting material, before engraving the indicia.

Preferably, said further layer is applied by silk-screening one or more coats of silk-screening ink on said first opaque layer.

A preferred form of indicator, together with a preferred method of making it, according to the invention, will now be described by way of example and with reference to the accompanying drawing, which is a section through the plaque attached to an electroluminescent panel.

In the drawing, an electroluminescent panel 10 has a layer 11 of double-sided transparent adhesive tape applied on its front surface. An indicator plaque 12, bonded to the tape 11, includes a two-ply laminate consisting of a transparent unplasticized PVC layer 13 press-bonded to an intermediate opaque white unplasticized PVC layer 14. Typical thicknesses for either of the layers 13 and 14 are in the range 0.005 in. to 0.020 in., though this is not to be taken as limiting. In this example the layers 13 and 14 are each 0.008 in. thick.

A layer 15 of grey or black matt PVC silk-screening ink, which is substantially non-reflecting, is applied by silk-screening several coats of the ink onto the front surface of the layer 14, to a thickness of (for example) 0.002*0.003 in. A protective layer 16 of hard scratchresistant transparent polyurethane lacquer is applied over the layer '15.

Indicia 17 are formed in the plaque by engraving. The indicia 17 are V-shaped in cross-section; they penetrate through the outer layers 16, 15 and the opaque layer 14 and a little way into the transparent layer 13, so as to form a clear portion 18 where the indicia intersects the layer 13'. Thus, light from the electroluminescent panel 10 passes to the eye of an observer positioned in front of the indicator plaque 12, through the clear portion 18 and is reflected from the white walls 19 of the indicia within the layer :14.

After engraving, colouring matter may be applied to the indicia.

It will be realised that the width of the clear portion of the indicia, i.e. the portion penetrating the translucent layer, is very small compared with the total width of the indicia. Examples of typical values for the width of the clear portion are 0.003 in., 0.004 in. and 0.008 in. for indicia letters having a nominal height of in., A; in. and A in. respectively.

Any suitable material may be used for the protective layer 16: it should be substantially harder than the layer next behind it, i.e. the layer 15 in the case of the example described above. The material of the layer 16 is preferably, though not necessarily, such as to give a matt finish.

If desired, a further layer of the material used for the layer 16 may be applied after the indicia have been engrayed, so as to protect the indicia as well as the layer 15. This is especially useful when colouring matter is applied to the indicia, in which case the second protective layer is applied after the indicia have been coloured.

The light source need not be electroluminescent, but may be of any suitable kind. Nor need it be attached to the plaque. If the light source is bonded to the plaque, any suitable bonding means may be used: for example, a clear synthetic resin in place of double-sided adhesive tape.

The indicia may be formed by any suitable means, though engraving is preferred.

If paint or ink is used for the layer 15, it may be applied by spraying or brushing instead of by silk-screening: but silk-screening is preferable since by this means the thickness of the layer can be more closely controlled.

The layers 13 and 14 may be of any suitable laminate material or materials, usually plastics. PVC is particularly suitable for both these layers, the PVC being in order to allow clear engraving.

The first opaque layer (i.e. layer 14 in the drawing) must have a reflectivity high enough to permit satisfactory reflection so that the reflecting portions of the walls of the indicia are easily visible under the ambient lighting conditions in which the indicator is to be used.

The angle between the reflecting walls of the indicia, i.e. the apex angle of the V, is such as to cause light entering the indicia from the translucent layer to be directed on to the walls of the indicia, so that the light is reflected from those parts of the walls formed on the opaque layer: the angle is preferably such as to reflect to the eye the maximum possible amount of light. The apex angle in general depends on the width of the indicia and it is not possible to lay down rules for its determination. This is best done by simple experiment for example by trying diiferent values of the apex angle in indicia of the width and height required, using the required light source in the ambient lighting conditions in which the indicator is to be used. The determination of the most satisfactory apex angle will then be largely a matter of personal judgment.

We claim:

1. A laminated indicator plaque including a translucent layer behind a first opaque layer having a substantially higher reflectivity to visible light than the translucent layer, wherein indicia, formed through the layer or layers in front of the translucent layer and penetrating part-way into the translucent layer, have a cross-section substantially in the form of a V, the apex angle of which is such that light transmitted through the translucent layer from behind is reflected from those portions of the walls of the indicia formed on said first opaque layer.

2. A plaque according to claim 1 including a further opaque layer, of substantially non-reflecting material, in front of said first opaque layer.

3. A plaque according to claim 1, wherein said first opaque layer is of unplasticized polyvinyl chloride.

4. A plaque according to claim 2, wherein said further opaque layer is of polyvinyl chloride.

5. A plaque according to claim 4, wherein said further opaque layer is of polyvinyl chloride ink.

6. A plaque according to claim 1, wherein the translucent layer is of unplasticized polyvinyl chloride.

7. A plaque according to claim 1, including a protective layer of translucent material substantially harder than the layer next behind it, arranged as the outside layer on the front of the plaque.

8. A plaque according to claim 7, wherein the protective layer is of polyurethane.

9. A plaque according to claim 1, wherein the indicia are coloured.

10. A method of making a laminated indicator plaque including a translucent layer behind a first opaque layer having a substantially higher reflectivity to visible light than the translucent layer, including the step of engraving indicia so as to give the indicia a cross-section substantially in the form of a V, so that the indicia extend through the layer or layers in front of the translucent layer and penetrate part-way into the translucent layer, and so that the apex angle of the V is such that light transmitted through the translucent layer from behind can be reflected from those portions of the walls of the indicia formed on said first opaque layer.

11. A method according to claim 10, including the step of applying to the front of said first opaque layer a further layer, of substantially non-reflecting material, before engraving the indicia.

12. A method according to claim 11, wherein said further layer is applied by silk-screening one or more coats of silk-screening ink on said first opaque layer.

13. A method according to claim 12, wherein said ink is of polyvinyl chloride.

14. A method according to claim 10, including the step of applying over the front of the plaque, after assembly of the remaining layers, a protective layer of translucent material substantially harder than the layer next behind it.

15. A method according to claim 10, including the step of applying colouring matter to the indicia after engravmg.

References Cited UNITED STATES PATENTS 1,888,584 11/1932 Cadieux 40-133 2,518,726 8/1950 Shlenker l61-6X 2,663,107 12/1953 Moler et a1. 40-133X 2,853,117 8/1958 Dibblee 156-268X 3,008,065 11/1961 Chamberlin 40-132X 3,027,668 4/ 1962 Hardesty 240-8.16X

HAROLD ANSHER, Primary Examiner R. A. KILLWORTH, Assistant Examiner US. Cl. X.R. 

